Piston type cigarette filter

ABSTRACT

A piston-type mouthpiece for a cigarette or cigarette holder includes an outer tube in which is a slidable cup-like piston with the open end facing the smoker. The piston face has a plurality of perforations which act as a filter. As the perforations become blocked and as the density of puffs increases during the smoking of the cigarette, the vacuum created in drawing on the cigarette gradually draws the piston toward the smoker. As the piston slides toward the smoker, openings in the cylindrical wall of the piston become aligned with openings in the outer tube so that air is drawn from the atmosphere directly into the smoker&#39;&#39;s mouth through these openings rather than through the tobacco column.

United States Patent Summers 51 Oct. 3, 1972 [54] PISTON TYPE CIGARETTEFILTER 2,145,733 1/1939 Palumbo ..l3l/ l 82 72 Inventor: Thomas W.Summers .l ff town Ky e arson Primary Examiner-Melvin D. ReinAttorney-Kane, Dalsimer, Kane, Sullivan & Kurucz [73] Assigneez Brown &Williamson Tobacco Corporation, Louisville, Ky. 57 ABSTRACT [22] Filed:A piston-type mouthpiece for a cigarette or cigarette 211 App] 93 5 0holder includes an outer tube in which is a slidable cup-like pistonwith the open end facing the smoker. The piston face has a plurality ofperforations which [52] US. Cl ..131/10 A, 131/ l0.3,1:l;3;{ 19g.i actas a filter. AS the perforations become blocked i and as the density ofpuffs increases during the smokg "A24d 01/04 13/04 ing of the cigarette,the vacuum created in drawing on 1 o are "131/ 6 35 the cigarettegradually draws the piston toward the smoker. As the piston slidestoward the smoker, openings in the cylindrical wall of the piston become[56] References and aligned with openings in the outer tube so that airis UNITED STATES PATENTS drawn from the atmosphere directly into thesmokers mouth through these openings rather than through the 3,512,5375/1970 Pelletier ..l3l/ 198 A X tobacco column 2,764,513 9/1956 Brothers..l31/l0.5 3,335,733 8/1967 Brooks ..l3 l/10.5 X 8 Claims, 3 DrawingFigures P'A'IEmEnuma m2 3.695.274

INVENTOR rw/ms n4 SUMMERS ATTORNEY s' PISTON TYPE CIGARETTE mmBACKGROUND OF THE INVENTION This invention relates to cigarettes orcigarette holders and, more particularly, to an improved filteringelement within the mouthpiece of the cigarette or holder whichautomatically moves toward the smoker as the pressure drop of the filterincreases and causes openings in the element and mouthpiece outer bandto register, allowing a portion of the inhaled air to be drawn directlyfrom the atmosphere. In conventional ventilated cigarettes theventilation reduces tar and nicotine excessively during the early puffs.

Some of the earlier patents disclose cigarette filters which seek toremedy this problem by providingperforations or openings to mix air withthe smoke, which can be varied by the smoker to suit his taste.

It is a principal object of this invention to provide an automatic meansof increasing the amount of ventilating air as the cigarette is smoked.

Another object of this invention is to provide a piston type filterwhich is so constructed that it has the appearance and qualities of aconventional filter forming a part of a cigarette or holder and stillfunctions in the manner herein described.

Another object of this invention is to provide a filter which isefficient for its intended purpose and simple and economical tomanufacture.

SUMMARY OF THE INVENTION The present invention covers a mouthpiece for acigarette or cigarette holder in which a cup-like piston is slidablewithin a tube forming the outer wrap of the mouthpiece. The face of thepiston is provided with a plurality of holes or perforations which serveas afilter. During smoking of the cigarette the holes become clogged andthe density of the smoke stream is increased causing the pressure dropof the cigarette to increase. The vacuum thus created in drawing on thecigarette causes the piston to move toward the smoker. The cylindricalwall of the piston is provided with a number of ports or openings whichare covered by'the outer wrap prior to smoking of the cigarette. As thepiston moves toward the smoker the ports in the piston overlap theperforations in the outer wrap allowing a portion of the inhaled air tobe drawn from the atmosphere and mix with the air drawn through thetobacco column. Although the ports in the piston and the perforations inthe outer wrap may be of any shape, it has been found preferable to havethe ports in the piston so shaped that the size of the overlap of theports and the flow of air from the atmosphere will increase as thepiston moves toward the smoker.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages willbecome apparent from the following detailed description which is to betaken in connection with the accompanying drawings illustrating asomewhat preferred embodiment of the invention in which:

FIG. 1 is a view of a cigarette showing the piston type mouthpiece ofthis invention;

FIG. 2 is a cross-sectional view along the line 2-2 of FIG. 1; and

FIG. 3 is a cross-sectional view along the line 3-3 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 of thedrawings, there is shown a cigarette 10 encased in an outer wrap 12 witha mouthpiece 11 of this invention. Slidable within the outer wrap 12 isa cup-like piston 13 (FIG. 2) provided with holes or perforations 14which act as a filter for air being drawn through thetobacco 15. Thepiston may be made of various materials, but nylon and polyethylenearethe most preferred. It has been found preferable to use between sevenand I1 holes, each having an area of 0.46 square millimeters, althoughsuch area may be varied between 0.1 and 0.7 square millimeters. Thetotal area of these holes would be within the approximate range of l to5 square millimeters. The piston has'ports 16 in the side covered by theouter wrap. Although the number of such ports 16 may vary in number andsize, it has been found that three or four ranging from I to 16 squaremillimeters will not weaken or destroy the strength of the piston. Thereare also perforations 17 in the outer wrap, which likewise may vary innumber and size. In the initial position of the piston, before thecigarette is smoked, the perforations 17 in the outerwrap are covered onthe inside by the wall of the piston to prevent air from the atmospherebeing inhaled by the smoker through such perforations. The size of theports is defined by the degree of perforations in the outer wrap. It isdesirable to have the overlap of ports and perforations to have apressure drop approximately between 5 and 30 inches at a 17.5 cc/sec.flow rate. For example, two holes each with an area of 0.224 squaremillimeters or one hole with an area of 0.46 square millimeters can beused. The pressure drop of the overlap of the piston ports and outerwrap perforations must be balanced with the piston face. It is desirableto maintain a total cigarette pressure drop during smoking withinreasonable limits between 2 and 7 inches H O. Thus, if it is desirableto use a relatively large area for the holes in the piston face, whichwould subsequently increase pressure drop upon smoking by a smallamount, then a relatively small area in the overlap would be necessaryto maintain the total cigarette pressure drop within practical limits.Likewise for a small hole area in the piston face, a relatively largeoverlap area would be required. The equation by which these pressuredrops are related is:

where P, is the tobacco section pressure drop;

P is the pressure drop of the hole in the face of the piston; and

P is the pressure drop of the overlap.

Each port 16 in the piston is shown in the shape of a triangle with theregistering perforations 17 in the outer wrap in the shape ofrectangles. Since the main object is to have the overlapping ports andperforations form an air opening which will become larger as the pistonmoves toward the smoker, it will be apparent that such ports can bevaried in shape and combinations of shapes to achieve that result. Forexample, the overlapping ports could be rectangles, circles, trianglesor similar figures.

The operation of the filter device should be clear from the foregoingdescription. The invention provides a device which can be connected to acigarette either as a cigarette holder or as a unitary filter cigarette.It will be understood that this filter device can also be used with aconventional cellulose acetate filter at either end or inside thepiston. It does not detract from the holder or cigarette, is simple andeconomical to manufacture, and operates effectively.

Thus, among others, the several aforenoted objects and advantages aremost effectively attained. Although a single somewhat preferredembodiment of the invention has been disclosed and described in detailherein, it should be understood that this invention is in no senselimited thereby and its scope is to be determined by that of theappended claims.

Having thus described the invention, what is claimed l. A filter deviceadapted to be interposed between the tobacco end and the mouthpiece endof a smoking device comprising:

a sleeve forming the outer wrap of the device and having at least oneopening in its side wall,

a tubular piston slidable in said sleeve and having at least one port inits side wall, the said port being interposed between the said openingand the tobacco end of the device and the the tubular side wall of saidpiston covering the said opening when the piston is in its initialposition,

said opening and said port when in registry forming a free air passagewhen the said piston moves from its initial position toward themouthpiece end,

' said opening and said port having predetermined dimensions whichincrease the air passage area as the said piston moves toward themouthpiece end,

the face of said piston adjacent said tobacco end having a plurality ofperforations,

said piston being adapted to move axially toward the mouthpiece end inresponse to a pressure differential across the said face as the smokerdraws on the device, whereby the piston will move until sufiicient airenters the air passage formed by the overlapping port and opening andthere is no pressure difierential across the face.

2. The invention of claim 1 wherein the number and size of perforationsin the face of the piston shall be such that the resistance of air flowthrough the piston face is within the values defined by 0.01 -0.1 inchesH O pressure drop at 17.5 cc/sec.

3. The invention of claim 1 wherein the number of perforations in theface of the piston shall be between seven and 11.

4. The invention of claim 3 wherein the area of each perforation shallbe between 0.1 and 0.7 square millimeters.

5. The invention of claim 1 wherein the number of ports in the side wallof the piston shall be between one and five.

6. The invention of claim 1 wherein the overlapping ports and openingsshall form an air opening having a total area ranging in size from'0z25to 5 square millimeters, 1

7. The invention of claim 1 wherein the ports shall be so shaped thatthe air opening formed by the overlapping ports and openings shallincrease in dimension as the piston slides from its initial position toa position w r th 0 ni fll e'terwit the rts.

h Tl'ie ine ntg i ofc aim where in thePgorts are triangles with theirapexes pointing in the direction of the smoker.

Disclaimer 8,695,274.Th0mas W. Summew-s, J effersontown, Ky. PISTON TYPECIGA- BETTE FILTER. Patent dated. Oct. 3, 197 2. Disclaimer filed Apr.27, 1973, by the assignee, Brown c6: Williamson Tobacco Owpomtz'on.

Hereby enters this disclaimer to claim 2 of said patent.

[Oficial Gazette N ovember 6, 1.973;]

1. A filter device adapted to be interposed between the tobacco end andthe mouthpiece end of a smoking device comprising: a sleeve forming theouter wrap of the device and having at least one opening in its sidewall, a tubular piston slidable in said sleeve and having at least oneport in its side wall, the said port being interposed between the saidopening and the tobacco end of the device and the the tubular side wallof said piston covering the said opening when the piston is in itsinitial position, said opening and said port when in registry forming afree air passage when the said piston moves from its initial positiontoward the mouthpiece end, said opening and said port havingpredetermined dimensions which increase the air passage area as the saidpiston moves toward the mouthpiece end, the face of said piston adjacentsaid tobacco end having a plurality of perforations, said piston beingadapted to move axially toward the mouthpiece end in response to apressure differential across the said face as the smoker draws on thedevice, whereby the piston will move until sufficient air enters the airpassage formed by the overlapping port and opening and there is nopressure differential across the face.
 2. The invention of claim 1wherein the number and size of perforations in the face of the pistonshall be such that the resistance of air flow through the piston face iswithin the values defined by 0.01 -0.1 inches H2O pressure drop at 17.5cc/sec.
 3. The invention of claim 1 wherein the number of perforationsin the face of the piston shall be between seven and
 11. 4. Theinvention of claim 3 wherein the area of each perforation shall bebetween 0.1 and 0.7 square millimeters.
 5. The invention of claim 1wherein the number of ports in the side wall of the piston shall bebetween one and five.
 6. The invention of claim 1 wherein theoverlapping ports and openings shall form an air opening having a totalarea ranging in size from 0.25 to 5 square millimeters.
 7. The inventionof claim 1 wherein the ports shall be so shaped that the air openingformed by the overlapping ports and openings shall increase in dimensionas the piston slides from its initial position to a position where theopenings fully register with the ports.
 8. The invention of claim 7wherein the ports are triangles with their apexes pointing in thedirection of the smoker.